Various mediums are being used as a recording medium for inkjet recording, and a high-definition image quality is required not only for inkjet exclusive paper but also for commercially available plain paper and printing mediums such as fine paper, coat paper and art paper. A pigment is preferred as an ink color material capable of giving fastness such as water resistance and light resistance on plain paper or a printing medium, and studies on an aqueous pigment ink are being variously made, including the aspect of cost. Among these, an azo pigment is preferably used as a yellow pigment for inkjet recording.
However, it is revealed that density unevenness and streak unevenness are produced when the ink is aged for a long period of time or at a high temperature.
As an aqueous ink for inkjet recording, a water dispersion for inkjet recording having an aqueous pigment dispersion containing C.I. Pigment Yellow 74 and an anionic group-containing organic polymer compound is disclosed (see, for example, Patent document 1). Specifically, it is indicated that when C.I. Pigment Yellow 74 is used as a pigment and a copolymer of n-butyl methacrylate, n-butyl acrylate, 2-hydroxyethyl methacrylate, methacrylic acid and styrene is used as a dispersant, dispersibility and dispersion stability can be ensured and a sharp image can be formed.